1. Field of the Invention
The present invention relates to a brake control system for a vehicle with a dual hydraulic pressure circuit system, wherein the braking force is applied appropriately to wheels in each hydraulic pressure circuit, when a brake pedal is depressed.
2. Description of the Related Arts
Recently, instead of a proportioning valve, it is proposed to employ electromagnetic valves for a braking force distribution control. For example, a Japanese Patent Laid-open Publication No.6-144179 discloses that a rear standard wheel speed is adjusted to be equal to or greater than a front standard wheel speed by actuating pressure control valves (inlet valve and outlet valve) connected to rear wheel brake cylinders to control the braking force applied to the rear wheels, so that a front and rear braking force distribution is approximated to an ideal front and rear braking force distribution. According to the publication, the braking force applied to the rear wheels is controlled such that the rear standard wheel speed is adjusted to be equal to or greater than the front standard wheel speed. In other words, the rear standard wheel speed is controlled not to be smaller than the front standard wheel speed. Therefore, if the braking force applied to the front wheels were reduced due to fade or the like in the front braking system, a decreasing rate of the front wheel speed would be reduced, so that the braking force to the rear wheels might be reduced excessively. As a result, the vehicle speed may not be decreased appropriately.